Q: How many animals must I slaughter for Udhiyah?
A: It is explicitly stated that one sheep/goat is sufficient for a man, his family, and those in his home.
A camel or cow is sufficient for seven.
The slaughter will be based on each individuals’ intention regardless is they all intended it as an act of devotion or if some intended devotion and some just wanted the meat. Or if some of them were Muslim seeking devotion and some were not. Each person shall have what they intended.
Source: Sharh al-Muntaha